Will a performance intercooler increase fuel mileage? And What else can I expect to gain from a new one other than lower EGTs

 

Probably a little more power if you're pushing a lot of air. They're a few bucks over a grand, though. Probably other things get you more power until you got a lotta air going through the stock intercooler. Some people use water injection after that.

 

The intercooler is of little gain (despite what banks ads say) other than egt, which wont matter much either if stock, until your way up in hp. That was roughly my first aftermarket piece since I hit that deer shortly after buying the truck back in 05. Not much gain over all but I could run the edge all the way up and did always have lower egts than everybody else.

 

An intercooler would be an absolute waste of money for your application. In a diesel application the intercooler almost never makes meaningful Hp gains, but a good aftermarket unit will help control egt's...Egt's are not your problem.

A good programmer (Smarty) will help a bit with fuel economy.